本文關(guān)鍵詞： 雙排樁 滑裂面 冠梁 剛度 空間效應(yīng) 影響長度 穩(wěn)定 加固　出處：《華南理工大學(xué)》2013年博士論文　論文類型：學(xué)位論文

【摘要】：雙排樁支護(hù)結(jié)構(gòu)是近年來興起的一種新型深基坑支護(hù)結(jié)構(gòu),其側(cè)向剛度大,能有效控制支護(hù)結(jié)構(gòu)的變形,而且受力條件和整體穩(wěn)定性好、施工方便,逐漸成為深基坑支護(hù)結(jié)構(gòu)的優(yōu)選方案之一。國內(nèi)外學(xué)者對雙排樁支護(hù)結(jié)構(gòu)進(jìn)行了大量的研究,研究成果對實際工程中的許多方面具有很好的指導(dǎo)意義,但由于雙排樁支護(hù)結(jié)構(gòu)受力復(fù)雜,在一些方面實踐先行,理論滯后,從而限制了該種支護(hù)結(jié)構(gòu)的發(fā)展。目前階段而言‘,在考慮樁頂冠梁平面外實際剛度計算方面、空間效應(yīng)冠梁的影響長度方面、不同潛在滑動面安全系數(shù)的極限平衡數(shù)值積分求解方面、滑動面的分布規(guī)律以及基坑加固等方面研究有所欠缺,本文在歸納整理了現(xiàn)有雙排樁支護(hù)結(jié)構(gòu)體系的國內(nèi)外研究成果基礎(chǔ)上,基于均質(zhì)粘性土層的地質(zhì)條件,通過理論推導(dǎo)、分析和數(shù)值模擬等方法,對深基坑雙排樁支護(hù)結(jié)構(gòu)體系研究中存在的上述薄弱環(huán)節(jié)進(jìn)行了有益的補充和完善,本文主要開展的研究工作和成果如下： 1.提出了考慮冠梁平面外實際剛度計算雙排樁支護(hù)結(jié)構(gòu)的內(nèi)力和變形的理論計算方法,并對比分析冠梁平面外假設(shè)無限剛與實際有限剛對樁身內(nèi)力和位移的影響。該方法基于winkle假定,引入冠梁平面外實際剛度的影響因素,對雙排樁支護(hù)結(jié)構(gòu)進(jìn)行理論分析,在此基礎(chǔ)上建立各段樁體的撓曲微分方程,然后根據(jù)各段樁體端點在幾何變形和內(nèi)力上的連續(xù)性關(guān)系以及相應(yīng)的邊界條件,采用數(shù)學(xué)近似方法冪級數(shù)求解各段撓曲微分方程,并求導(dǎo)各段撓曲方程的解得出雙排樁各點的內(nèi)力及變形,通過分析冠梁平面外假設(shè)無限剛與實際有限剛的計算結(jié)果可以得出：1)冠梁的剛度增大可減少前、后排樁的位移,但會增大前、后排樁樁身彎矩；2)冠梁剛度的變化對后排樁樁身彎矩的影響比前排樁稍大；3)冠梁的剛度變化對樁身彎矩的影響幅度和對位移的影響幅度比較接近。該方法與現(xiàn)行假設(shè)冠梁無限剛的理論計算方法相比更符合工程實際情況,為考慮冠梁實際剛度求解雙排樁的變形和內(nèi)力提供了一種可行的理論計算方法； 2.對雙排樁支護(hù)結(jié)構(gòu)進(jìn)行了三維數(shù)值模擬,研究了雙排樁支護(hù)結(jié)構(gòu)在空間效應(yīng)下的受力和變形特性,在此基礎(chǔ)上,研究了冠梁與支護(hù)樁的剛接和鉸接連接方式、基坑的長邊長度、短邊長度、開挖深度、冠梁剛度、土層粘聚力和摩擦角、支護(hù)結(jié)構(gòu)排距和樁距等主要設(shè)計參數(shù)與空間效應(yīng)冠梁影響長度的關(guān)系,通過分析不同參數(shù)變化下的冠梁影響長度的規(guī)律得出：基坑短邊長度、開挖深度和支護(hù)結(jié)構(gòu)排距的變化對冠梁影響長度都有較大影響；基坑長邊長度、粘聚力、摩擦角、冠梁剛度以及支護(hù)結(jié)構(gòu)樁距的變化對冠梁的影響長度影響很小。 3.提出了雙排樁支護(hù)基坑在不同潛在滑動面的簡化整體穩(wěn)定安全系數(shù)積分計算方法,該方法以Bishop法原理為基礎(chǔ),建立適用于深基坑雙排樁支護(hù)結(jié)構(gòu)穩(wěn)定分析的簡單平面直角坐標(biāo)系,推導(dǎo)出潛在滑動面經(jīng)過基坑底部與前排樁交點圓弧等位置的簡化整體穩(wěn)定分析的安全系數(shù)積分表達(dá)式,并考慮可能出現(xiàn)的主動區(qū)、樁間土和被動區(qū)加固的情況,完善了安全系數(shù)在不同積分區(qū)間的積分表達(dá)式,然后編制了相應(yīng)的計算程序計算基坑穩(wěn)定安全系數(shù),通過計算結(jié)果的分析可以得出,滑動面經(jīng)過基坑底部與前排樁交點圓弧的安全系數(shù)為F1,滑動面經(jīng)過前排樁樁底圓弧的安全系數(shù)為F2,滑動面經(jīng)過后排樁樁底圓弧的安全系數(shù)為F3,而F1略大于F2,F2略大于F3,與有限元計算結(jié)果進(jìn)行對比分析,驗證了所提出方法的可行性,完善了極限平衡法數(shù)值積分求解安全系數(shù)在深基坑雙排樁支護(hù)結(jié)構(gòu)中的應(yīng)用。 4.對雙排樁支護(hù)結(jié)構(gòu)的基坑穩(wěn)定性進(jìn)行了數(shù)值分析,系統(tǒng)研究了基坑穩(wěn)定安全系數(shù)隨土層的粘聚力、摩擦角以及支護(hù)結(jié)構(gòu)的樁長和排距等設(shè)計參數(shù)而變化的規(guī)律得出：基坑的穩(wěn)定安全系數(shù)隨著粘聚力、摩擦角、支護(hù)結(jié)構(gòu)樁長和排距的增加而增加,穩(wěn)定安全系數(shù)受粘聚力和摩擦角的影響最大,受支護(hù)結(jié)構(gòu)樁長的影響較大,受支護(hù)結(jié)構(gòu)排距的影響較小。并且,總結(jié)了滑動面的分布特點和規(guī)律。 5.對雙排樁支護(hù)的基坑進(jìn)行加固分析,系統(tǒng)研究了主動區(qū)、樁間土和被動區(qū)加固對樁身內(nèi)力和變形特性的影響后得出：1)對于主動區(qū)加固,當(dāng)加固深度超出基坑深度,加固效果不明顯；2)對于被動區(qū)加固,加固深度或?qū)挾燃s為基坑深度的一半時最有效。 6.在以上工作基礎(chǔ)上提出進(jìn)一步開展相關(guān)研究工作的建議。
[Abstract]:The double - row pile supporting structure is a new kind of deep foundation pit supporting structure which has arisen in recent years . The lateral rigidity is large , it can effectively control the deformation of the supporting structure , and the stress condition and the whole stability are good , the construction is convenient , and it becomes one of the preferred schemes of deep foundation pit supporting structure . On the basis of summarizing the research results of the existing double - row pile support structure system , this paper makes a useful supplement and improvement to the weak links existing in the research of the double - row pile support structure system of deep foundation pit . The main research work and results are as follows : 1 . The theoretical calculation method for calculating the internal force and deformation of the double - row pile supporting structure considering the actual rigidity outside the plane of the crown beam is put forward , and the influence factors on the internal force and displacement of the pile body are analyzed . Based on the assumption of winkle assumption , the deflection differential equations of the two rows of piles are obtained . 2 . Based on the three - dimensional numerical simulation of the double - row pile supporting structure , the stress and deformation characteristics of the double - row pile supporting structure under the space effect are studied . Based on this , the relationship between the main design parameters of the crown beam and the supporting pile , the length of the long side of the foundation pit , the length of the short side , the depth of excavation , the row spacing of the foundation pit and the influence length of the crown beam are studied . The influence of cohesive force , friction angle , crown beam rigidity and support structure pile spacing on crown beam is very small . 3 . Based on Bishop ' s method principle , the integral expression of safety factor for the stability analysis of double - row pile supporting structure of deep foundation pit is established . The safety factor of the sliding surface passing through the arc of the bottom of the foundation pit and the intersection of the front row piles is F1 , the safety factor of the sliding surface passing through the arc of the bottom of the front row pile is F2 , the safety factor of the sliding surface passing through the bottom arc of the front row pile is F2 , the safety factor of the sliding surface passing through the bottom arc of the front row pile is F2 , the safety factor of the sliding surface passing through the bottom arc of the front row pile is F2 , the safety factor of the sliding surface passing through the bottom arc of the front row pile is F2 , the safety factor of the sliding surface passing through the bottom arc of the front row pile is F1 , the safety factor of the sliding surface passing through the bottom arc of the front row pile pile is F2 , the safety factor of the sliding surface passing through the bottom arc of the front row pile pile is F1 , the safety factor of the sliding surface passing through the bottom circular arc of the front row pile is F1 , the safety factor of the sliding surface passing through the circular arc of the front row pile pile is F1 , the safety factor of the sliding surface passing through the circular arc of the front row pile is slightly larger than F3 , and the application of the safety factor in the double - row pile supporting structure of the deep foundation pit is improved by improving the numerical integral solution safety factor of the limit equilibrium method . 4 . Based on the numerical analysis of the stability of the foundation pit of double row pile supporting structure , it is found that the stability safety factor of the foundation pit increases with the increasing of cohesive force , friction angle and pile length and distance of the supporting structure . The stability safety factor of the foundation pit increases with the increasing of cohesive force , friction angle , length and distance of the support structure . The stability safety factor is affected by the cohesive force and friction angle . 5 . After strengthening and analyzing the foundation pit supporting double - row piles , the influence of active area , pile - to - soil and passive area reinforcement on the internal force and deformation characteristics of pile body is studied . The results show that : 1 ) For the active area reinforcement , when the reinforcement depth exceeds the depth of the foundation pit , the reinforcement effect is not obvious ; 2 ) For the reinforcement of the passive zone , the reinforcement depth or width is about half of the depth of the foundation pit . 6 . On the basis of the above work , a proposal to further carry out the relevant research work is proposed .

【學(xué)位授予單位】：華南理工大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2013
【分類號】：TU753

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